This proposal outlines synthetic techniques to be investigated which are to be applied to several cytotoxic lactonic natural products. Further applications of a reaction sequence developed in this Laboratory which provides alpha-methylane gamma-butyrolactones having specific oxygenation necessary for cytotoxic activity, are outlined. The study relates to the synthesis of the cytotoxic tulipenolides which are related to elephantopin, which has been shown to have in vivo activity toward Walker 256 carcinoma in rats and lymphocytic leukemia in mice. A photochemical synthesis of the cytotoxic lignan steganangin and steganacin, which show sinificant in vivo cytotoxic activity against P- 388 leukemia in mice and in vitro activity against cells from human carcinoma of the nasopharynx. Work in both these areas is presently under way in this Laboratory.